The present invention relates to a sputtering target for forming a granular film of a magnetic recording medium in a vertical magnetic recording HDD (hard disk drive), and particularly relates to a Co—Cr—Pt-based sputtering target with oxides finely dispersed therein.
In the field of magnetic recording as represented by hard disk drives, materials based on Co, Fe or Ni, which are ferromagnetic metals, are being used as materials of a magnetic thin film in a magnetic recording medium.
As the magnetic thin film of a hard disk drive adopting the vertical magnetic recording method that has been put into practical use in recent years, often used is a composite material configured from a Co—Cr—Pt-based ferromagnetic alloy having Co as its main component and nonmagnetic inorganic particles. In addition, the foregoing magnetic thin film is often produced by sputtering a sintered compact sputtering target made from foregoing materials via a DC magnetron sputtering device in light of its high productivity.
Meanwhile, when sputtering is performed using a sputtering device, there is a problem in that particles are generated. It is known that most of the particles that are generated during the deposition of a granular film are caused by the oxides in the target structure. In recent years, since the floating height of a magnetic head is decreasing in a hard disk drive pursuant to the increase in recording density, the size and number of particles that are tolerable in a magnetic recording medium are becoming even more strictly regulated.
Various techniques are known in relation to a sputtering target for forming a granular film and its production method (for instance, Patent Documents 1 to 4). For example, Patent Document discloses a method for suppressing the aggregation of oxide particles, refining the target structure, and reducing the generation of particles by mixing a primary sintered compact powder, which is obtained by mixing, sintering and pulverizing a part of the raw material powder in advance, upon mixing and pulverizing the raw material powder using a ball mill or the like.